Senior Core Engineer

Unity Technologies SF•San Francisco, CA

About The Position

PolySpatial is the core technology behind Unity's support for visionOS, streaming Unity games into Fortnite, and iteration tools like Play to Device, Scene Recording, and AI data capture and analysis. Underneath all of it is a single model for connecting devices, users, applications, and even different game engines, and we're constantly finding new places to put it to work. We're looking for engineers eager to help us invent how different real-time 3D runtimes communicate and render under real-world constraints. You’ll work at the intersection of core engine tech, high-performance networking, distributed systems, and graphics. This is your opportunity to build the fundamental infrastructure for the next generation of interconnected game and 3D ecosystems. You’ll own critical tech that enables Unity to run as a guest within other processes, engines, and distributed systems. This is deep engine work requiring a holistic understanding of execution models, serialization, asset lifecycles, and runtime performance—all operating reliably in host environments we don’t control. You'll design systems that allow Unity to load, run, and synchronize assets when we don't own the main loop, design clean, extensible architecture, then drop into assembly to shave off milliseconds.

Requirements

Core Engine Expertise: Experience building or fundamentally extending game engine cores, middleware, or foundational systems (e.g., serialization, build pipelines, memory subsystems).
Architectural Vision + Practical Implementation : Design modular, testable systems, then implement and debug them yourself end-to-end
High-Performance Coding: Strong C++ and C# skills, with practical understanding of CPU caches, branch behavior, memory layout, and profiling.
Engine-Wide Breadth: Hands-on experience across multiple engine domains (e.g., physics, animation, input, assets) and how they interact.

Nice To Haves

Familiarity with compression, streaming, replication, authority models, RPCs, state diffing, delta encoding, or network protocols for real-time interactive systems.
Experience with determinism, replay systems and simulation consistency.
Deep knowledge of multithreading, job systems, lock-free techniques, and/or Unity DOTS.
Experience with MCP-style tool interfaces, training data generation, machine learning, or agentic workflows.

Responsibilities

Own and evolve critical subsystems across the engine stack, from low-level C++ to high-level C# APIs across editor, build, and runtime code.
Design and implement high-performance, extensible APIs intended for embedded, cross-process, and networked configurations.
Develop schemes to manage execution timing and resource contention within or between processes and over the network with minimal overhead
Orchestrate loading, change tracking, serializing, and synchronizing components and assets in bandwidth and latency-constrained environments.